1. Field of the Invention
The present invention relates to case opening and loading devices. In particular, the present invention relates to an improved downward case opening apparatus as part of a larger case opening, loading and sealing machine having a vertical magazine for holding case blanks. Blanks are loaded from the magazine into an overhead conveyor which transfers them to the opening apparatus, said apparatus utilizing vacuum suction, gravity and friction to open large numbers of cases in a short amount of time.
2. Description of the Prior Art
In the art, and in the industry, the terms "case" and "carton" (or "box") define two completely different things. A "case" refers to a generally large corrugated cardboard container into which a pre-determined number of smaller containers (e.g. cartons, bottles or cans) are placed for shipping and/or storage. A "case" of beer generally refers to twenty-four 24 cans or bottles of beer in such a corrugated cardboard container. The inside and outside surfaces of a "case" are smooth, but the typical case has wavy corrugated cardboard between such surfaces.
In contrast, a "carton" or "box" is defined by a generally smaller single-unit cardboard container into which a product (e.g. cereal or detergent) is placed. A "carton" of cereal is likely to be found on a grocery store shelf. A "case" might contain twelve (12) cereal boxes in it for shipping to the grocery store. A "carton" typically consists of one sheet of stiff cardboard, with no corrugation in between.
The present invention relates to the opening of larger "cases". Such cases are typically manufactured from a single piece of corrugated cardboard, or the like, and cut into a predetermined pattern and provided with indented fold lines to facilitate folding into rectangular containers. The manufacturer usually fold the pattern once to make it flat. This brings the opposite edges together so that they may be joined. These flat blanks are shipped in this compact form, and must be opened into a rectangular shape by the user for insertion of products and sealing.
There are numerous devices in the prior art designed to open flattened case blanks for the insertion of products or articles therein. There are also several carton/box opening devices designed to open cartons for the insertion of particular products therein. The primary differences between case-opening machines and carton-opening machines concern the volume (size) of the blanks to be opened, and the material out of which the blanks are made. Both of these aspects affect the speed at which the opening of blanks takes place. Cases are generally much larger than boxes, and therefore require machines that take up more space and are of more sturdy construction than carton opening machines.
Because of the high volume of container blanks that pass through case-opening machines, it is desirable to have a large magazine to hold the flattened blanks prior to being opened.
One of the most common methods of opening folded container blanks utilizes vacuum suction cups attached to the end of a movable arm in conjunction with a frictional surface. The arm swings up to bring the vacuum suction cup into contact with the lowermost container blank from a magazine. The blank is pulled from the magazine by the suction cup as the arm swings back down, and it is forced against a deflectional surface. This friction puts pressure on one or more corners of the flat blank which causes it to open. The opened blank is thereafter moved onto a conveyor mechanism for insertion of product and sealing. U.S Pat. Nos. 3,298,289, 4,066,009, 4,109,444, 4,197,790, and 4,471,601 utilize this method. Unfortunately, this method of opening blanks suffers from several disadvantages. Most importantly, it is slow because a single cycle requires the blank to be pulled down, opened, and moved completely off the arm before the next cycle can be started. A further disadvantage of this method is the requirement that the magazine of blanks be above the swinging arm, and that said magazine be tilted at an angle corresponding to the upswing of the arm. Tilted magazines are generally difficult to load with container blanks, and usually do not have very large capacity.
Several variations of the swinging vacuum arm and deflection surface method of opening container blanks are disclosed in U.S. Pat. Nos. 2,289,820, 3,293,998, 3,533,333, 3,564,980, 3,613,526, 4,331,435, 4,348,853, 4,531,931, 4,621,485, 4,629,446, and 4,892,513. Most of these patents utilize upper and lower vacuum suction cups in conjunction with a deflectional surface for opening container blanks. U.S. Pat. Nos. 3,613,526 and 4,531,931 utilize three (3) separate arms having suction cups thereon. However, each of these patents suffers from the drawback of slowness because of the lag time between cycles; and most also require tilted or small capacity magazines of blank containers.